Hidden from Magnetic View An electromagnetic cloak is a device within which fields cannot penetrate, but, more importantly, the itself does not disturb surrounding it. article placed in therefore vanishes view, creating no shadow or reflection. Such devices have been demonstrated, but only for particular band of frequencies. Confirming theoretical work that predicts such cloaking should be possible down to zero frequency, Gömöry et al. (p. 1466 ) designed dc magnetic field. With composite...

Future use of coated conductors in electric power applications like transmission cables, transformers or fault current limiters is sensitive to the amount dissipation AC regime. This paper analyses factors controlling loss typical configurations: self-field case when transport generates magnetic field, and applied field where orientation with respect superconducting layer plays a significant role.

The electromagnetic properties of a pancake coil in an AC regime as function the number turns is studied theoretically and experimentally. Specifically, loss, critical current voltage signal are discussed. coils made Bi2Sr2Ca2Cu3O10/Ag (BiSCCO) tape, although main qualitative results also applicable to other kinds superconducting such coated conductors. loss electrically measured using different pick-up with help transformer. One them avoids dealing huge inductance. In addition,...

The current distribution and the AC loss in a composite superconducting tape containing layer of magnetic material is calculated compared with experiments, showing very good agreement. situations an alternating uniform applied field or transport are studied. newly developed numerical model approximation to critical state model, adapted for applicability commercial finite element codes that solve vector potential. A substantial feature this procedure it can be carried out case when density...

A calibration free measurement method for determination of the magnetization loss superconducting samples exposed to external AC magnetic field is presented. The idea based on part power which supplied by source magnet generating field, in sample located. It uses a coil wound parallel as coil. To achieve necessary sensitivity, two identical systems are used, each consisting an and coil, one them containing other left empty. No and/or calculation constant required. confirm suitability this...

Many applications of ReBCO-coated conductors operate at low magnetic fields in the superconductor (below 200 mT). In order to predict critical current and AC loss these applications, it is necessary know anisotropy field dependence density fields. this paper, we obtain a formula for coated conductor as function local its orientation. Afterwards, apply pancake coil that constructed. We extract tape from measurements in-field several orientations. Numerical simulations correct effect...

In this work we demonstrate that the use of striated tapes from coated conductors (CCs) significantly reduces dissipation a cable made wound helically on round core when it is exposed to AC magnetic field. The coupling loss can vanish provided striations ensure electrical insulation between filaments and length corresponds an entire number lay pitches. our study compare magnetization in two models field perpendicular their longitudinal axis. overall geometry was identical: each consisted...

Many applications of ReBCO coated conductors contain stacks pancake coils.In order to reduce their high AC loss, it is necessary understand the loss mechanisms.In this article, we measure and simulate critical current, Ic, in coils ("pancakes").We construct up 4 pancakes them by electrical means.We also obtain anisotropic field dependence Jc from Ic measurements tape.This only input simulations, together with coil dimensions.After validating our computations measurements, many pancakes,...

Many large-scale applications require electromagnetic modelling with extensive numerical computations, such as magnets or three-dimensional (3D) objects like transposed conductors motors and generators. Therefore, it is necessary to develop computationally time-efficient but still accurate methods. This article develops a general variational formalism for any relation applies model coated-conductor coils containing up thousands of turns, taking magnetization currents fully into account. The...

High-temperature superconductor (HTS) machine is a promising candidate for the electrical aircraft propulsion due to its great advantage in high power density. However, HTS always suffers problem of low thermal stability during quench. In this article, we apply no-insulation (NI) coil technique on rotor windings machines enhance and safety aircraft. The NI experience ripple magnetic fields, which leads induced eddy currents through turn-to-turn contacts. This current accompanying losses will...

The case of ac transport at in-phase alternating applied magnetic fields for a superconducting rectangular strip with finite thickness has been investigated. field is considered perpendicular to the current flow. We present numerical calculations assuming critical state model distribution and loss various values aspect ratio, amplitude. A rich phenomenology obtained due metastable nature state. perform detailed comparison analytical limits we discuss their applicability actual geometry...

The design of a superconducting coil from high-performance REBCO coated conductors is often complicated because complex anisotropy the critical current density <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> <sub xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> . It important to understand how much detail this feature must be taken into consideration in prediction maximum achievable and expected ac loss. We present results investigation...

In several superconducting applications, as, for example, in some supercondcuting generators, motors, and power transmission cables, the superconductor experiences a changing magnetic field DC background. Simulating losses caused by this AC ripple is an important task from application design point of view. work, we compare two formulations, H-formulation minimum energy variation-formulation, based on eddy current model (ECM) critical state (CSM), respectively, simulating biased coated...

Magnetic diverters are commonly used in order to reduce the AC loss superconducting coils. However, they have not been proved work on YBa2Cu3O7−x-coated conductor Moreover, modeling tools required for predicting resulting and understanding mechanisms. In this paper, a coated pancake coil with ferromagnetic diverter is measured simulated. The magnetic reduces but critical current practically does change. Our simulations show that wider than measurements can below of single strip. Therefore,...

Non-uniformity of superconductor properties, e.g. a critical current reduction close to the edge coated conductor (CC) tape could degrade its performance in some power applications. Reliable characterization such non-uniformity and understanding mechanism requires investigation character causes degradation. In this paper spatial distribution density across width CC is studied. Three different experimental methods allowing estimation local were utilized for purpose: (i) magnetic field mapping...

The assembly of meander shaped coated conductor tapes by the Roebel technique is a promising way to manufacture high current cables with low ac losses. application longitudinal striations single strands can be an option create filament structure for further possible reduction Due complex strand geometry, it was important identify reliable produce such structures using picosecond-infrared (IR) laser groove etching process. We analyzed effects on magnetization loss behavior comparing losses...

Cloaking a three-dimensional object in free space from electromagnetic waves has recently become theoretical possibility, although practical implementations can only be made reduced schemes. If static fields are involved, requirements less restrictive and some realizations have been possible. Here we present third regime between the full wave cases. We experimentally demonstrate that cloak constructed under dc conditions keep cloaking properties for applied magnetic oscillating at low...

Coated conductor (CC) tapes often exhibit critical current, Ic, which fluctuates along the length coordinate, x, leading to an Ic(x) dependence. The need reduce price of these does not favor a decrease in variation Ic near future. Therefore, it is reasonable develop method for estimating possible impact such fluctuating transport ability on performance superconducting devices. Fortunately, providing data together with delivered becoming standard approach among CC tape producers, and in-depth...

We report here a study on the role of crystallinity magnetoresistive properties self-doped La0.8MnO3−δ thin films. Films have been grown by liquid-source metalorganic chemical vapor deposition technique two different single crystals: SrTiO3 (001) and Al2O3 (012). Epitaxial films are obtained strontium titanate show high magnetoresistance peak at low fields: maximum effect in vicinity magnetic transition temperature, negligible 50 K below. Polycrystalline observed sapphire; they exhibit lower...

Coupling ac loss between superconducting filaments or tapes produces additional heating, complicating the cryogenics of applications and reducing their efficiency. Predicting coupling currents that they generate in general 3-D samples require numerical computations. These may reduce by sample optimization are necessary for device design. In this work, we model measure (and hysteresis) soldered striated tapes. is measured at 72 144 Hz applied fields up to 100-mT amplitude frequencies from 2.4...

Abstract A common feature of commercially available conductors based on high-temperature superconducting compounds is the fluctuation critical current along length. Fortunately, practice adopted by manufacturers nowadays to supply detailed I c ( x ) data with conductor. Compared knowing just average current, this should also allow a much better prediction conductor performance. Statistical methods are suitable for purpose in case when fluctuations regular at low end distribution. However,...

State-of-the-art wireless power transfer (WPT) systems, based on conventional copper coils, are known to exhibit efficiencies well above 90% when operated in the resonantly coupled mid-range regime. Besides full system efficiency, area- and weight-related densities of transmission coils key figures merit for high applications. This article reports a fully functional WPT system, consisting single pancake high-temperature superconducting (HTS) transmitter receiver side, which exceeds density...

Critical currents measured on a commercial Bi-2223/Ag tape in applied magnetic fields ranging from zero to 100 mT are analysed order demonstrate the validity of phenomenological description proposed by authors for flux pinning polycrystalline high-temperature superconductors low fields. The four-parameter model is generalization Kim formula describing field dependence critical current density. When combined with finite-element calculation, it able predict different orientations an average...

In this paper, an optimization method to determine the magnetic field dependence of intrinsic critical current density, Jc(B), is introduced. First all measured in various external fields. Then Jc(B)-dependence that fits optimally measurements searched for. these computations self-field sample taken into account and thereby performed low fields, below 0.1 T, can be exploited. Here YBCO material described by Kim model, which modified include anisotropy also. Thus, there are four parameters...

Reduction of dissipation at the transport alternating current as well when exposed to a time varying magnetic field has been observed in tape from high-temperature superconductor Bi2Sr2Ca2Cu3O10 covered by Ni sheath edges. The improvement critical can explain this achievement only part. Analysis experimental data shows that also more favorable pattern flux penetration should take place.